JPH0840967A - Method for producing high-purity isoaldehyde - Google Patents

Abstract

(57) [Summary] [Objective] In the step of separating and purifying a mixed aldehyde product, even if the content of light components such as water in the mixed aldehyde product increases, high-purity isoaldehyde can be stably obtained.
And to provide an economical way to obtain. [Structure] Normal aldehyde produced by hydroformylation reaction of propylene or butene, isaldehyde, and a mixed aldehyde product containing 0.01 wt% to 5.0 wt% of water are used in the first distillation column to produce a light product of isaldehyde and aldehyde. A method for producing a high-purity isoaldehyde, which comprises distilling and separating into fractions and purified normal aldehyde, and then distilling into a light fraction of aldehyde and purified isoaldehyde in a second distillation column.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing high-purity isoaldehyde in a step of separating and purifying a mixed aldehyde product. More specifically, the mixed aldehyde product after separating the catalyst liquid containing most of the unreacted olefin, solvent and by-product high boiling point product from the product stream containing the mixed aldehyde produced by the hydroformylation reaction of propylene or butene The present invention relates to a method for producing high-purity isoaldehyde in a step of separating and purifying purified normalaldehyde and purified isoaldehyde.

[0002]

2. Description of the Related Art A method for producing an aldehyde by a hydroformylation reaction of an olefin is conventionally known and has been commercialized worldwide. For example, in Japanese Examined Patent Publication No. 51-1687, rhodium is used as a catalyst in a complex bond with carbon monoxide and a trivalent organic phosphorus ligand, a high boiling point liquid condensate is used as a solvent, and olefin and carbon monoxide Hydrogen and a temperature range of about 50 to 145 ° C., a total pressure of carbon monoxide and hydrogen of 450 psia or less, and a partial pressure of carbon monoxide not more than about 75% of the total pressure. A method for obtaining an aldehyde rich in a normal form as a product by contacting with the above is disclosed.

According to this method, as products, in addition to the desired products, normal aldehyde and isaldehyde, alcohols, aldol condensation dehydration products such as 2-ethyl-3-propylacrolein, and aldehyde dimers as by-products. , High-boiling condensation products such as trimers and tetramers are obtained. All of these by-products are produced due to the high reactivity of the produced aldehyde, alcohol is produced by hydrogenation of the produced aldehyde by hydrogen in the reactor, and other by-products themselves are uncatalyzed and relatively It is produced as a result of the condensation reaction despite the low temperature.The reaction mechanism is that aldol condensation occurs first, and acrolein is produced by the dehydration reaction of the produced aldol, and the diene such as thisenko reaction, transesterification reaction and cannizaro reaction is generated. The mutation reaction produces dimers, trimers and tetramers. Such a condensation dehydration reaction does not always occur although it varies to a certain extent depending on various hydroformylation reaction conditions, that is, reaction temperature, reaction pressure, solvent used, catalyst ligand used, and various other conditions. is there. Therefore, in such a hydroformylation reaction, water as a product of the condensation dehydration reaction is always produced as a by-product.

Generally, the hydroformylation reaction product contains some amount of water, but as described above, in addition to the by-product water of the condensation dehydration reaction, a mixed gas of hydrogen and carbon monoxide as a raw material. (This is called oxo gas)
The water that is entrained together with and brought into the hydroformylation reaction region cannot be ignored. The concentration of entrained water in oxo gas varies depending on the type of oxo gas production process and operating conditions. For example, methane and naphtha are subjected to a steam reforming reaction and a water gas reaction at a high temperature of about 800 ° C. with carbon dioxide, steam, etc., or a partial oxidation reaction to produce hydrogen,
Obtain a decomposition gas composed of carbon monoxide, carbon dioxide, steam, etc., and then introduce this decomposition gas into an absorption tower to absorb and remove carbon dioxide with an alkanolamine or hot potassium carbonate aqueous solution (this is called a decarboxylation step). When the purified oxo gas is obtained by the above process, the obtained purified oxo gas contains saturated water vapor under the operating pressure and temperature conditions of the absorption tower in the decarbonation step, so most of the water content is compressed and cooled in the subsequent step. Even if removed, usually 0.2 to 0.7 vo
Contains 1% water as steam. This water is directly introduced into the hydroformylation reaction region. As described above, water is always present in the conventional hydroformylation reaction region, which is a cause of deterioration of the hydrogenation catalyst when the aldehyde produced is hydrogenated in the subsequent step.

Various methods have conventionally been adopted for the operation of separating a hydroformylation reaction product containing an aldehyde as a main component from the hydroformylation reaction region. For example, in JP-A-52-125103, a gaseous recycle stream consisting of an oxo gas and an olefin is fed into a hydroformylation reaction zone to produce an olefin, a generated aldehyde,
A high boiling aldehyde condensation product which is a solvent, a soluble rhodium catalyst complexed with carbon monoxide and a triarylphosphine, and a liquid triphenylphosphine are supplied to a liquid material, and the olefin, oxo gas, and vaporized aldehyde produced from the liquid material are supplied. A method of forming a gaseous recycle stream by removing a vaporous mixture consisting of an evaporated high-boiling point aldehyde condensation product commensurate with the side reaction production rate and recovering the produced aldehyde and the aldehyde condensation product from the vaporous mixture is formed. It is disclosed.

Further, in Japanese Patent Laid-Open No. 54-89974, a method for separating the aldehyde formed from the hydroformylation reaction region is described as a soluble rhodium catalyst complex-bonded with a high boiling aldehyde condensation product which is a solvent, carbon monoxide and a triarylphosphine. It is possible to introduce a liquid product consisting of the free triarylphosphine, and the produced aldehyde into a falling film evaporator, and introduce a partially vaporized gas-liquid mixture into a distillation column to obtain the produced aldehyde as a reflux liquid. It is disclosed.

The product stream remaining after separating the catalyst liquid containing most of the unreacted olefin, solvent and by-product high boiling point product from the hydroformylation reaction region as described above is hereinafter referred to as a mixed aldehyde product. In addition to aldehyde, which is the main component, there are very small amounts of dissolved gas (hydrogen, carbon monoxide, methane, carbon dioxide, etc.), a small amount of unreacted olefin that is a light component of aldehyde, paraffins and Water, a small amount of solvent which is a high boiling point of aldehyde, and a high boiling point by-product.

The mixed aldehyde product is mainly an isomer mixture of normal aldehyde and isaldehyde, but it is rarely used as a reaction raw material in the subsequent step as it is, and in general, normal aldehyde is normally used. It is purified and separated into and isoaldehyde. As disclosed in US Pat. No. 5,227,544, for example, when normal butyraldehyde is condensed and hydrogenated to produce 2-ethylhexanol, isobutyraldehyde contained as an impurity finally becomes isooctanol. This is to prevent the quality of 2-ethylhexanol, which becomes a product, from being significantly changed. On the other hand, as for isobutyraldehyde, for example, when hydrogenating isobutyraldehyde to produce isobutanol, normal butyraldehyde contained as an impurity significantly reduces the quality of isobutanol to be a product or maintains the quality. This is for avoiding a significant increase in the distillation purification cost.

Regarding the method for purifying and separating the above-mentioned mixed aldehyde product, the following methods have been conventionally known. (1) As the most classical method, the mixed aldehyde product is fed to one distillation column to obtain an isoaldehyde containing a light component as a distillate and a normal aldehyde containing a heavy component as a bottom product. Method. (2) Using two distillation columns for purification, an isoaldehyde containing a light component is obtained as a distillate from the first distillation column, and the bottoms thereof are fed to the second distillation column, A method of obtaining normal aldehyde as a distillate and obtaining a heavy component as a hydroformylation reaction solvent as a bottom liquid. (3) As a method disclosed in JP-A-4-273841, a mixed aldehyde product is fed to one distillation column, and an isaldehyde having a small light content is obtained from a side stream below the theoretical stage by two stages from the top of the column. How to get.

[0010]

However, in the conventional methods such as (1) and (2) above, light components such as water, olefins and paraffins in the mixed aldehyde product to be fed (water has a boiling point as a boiling point). Although it is higher than aldehydes, it behaves similarly to other light components because it azeotropes with aldehydes. Therefore, after that, water is also included in the light components.) The absolute amount of light components in the isoaldehyde liquor taken is equal to the remainder of the absolute amount of light components in the mixed aldehyde product fed which was externally purged from the top as uncondensed gas. Regarding the composition of the mixed aldehyde product, the iso form is generally lower than the normal form as a ratio due to commercial demand. Compared to that, it is far less. Therefore, the light components fed to the distillation column are concentrated in the distillate, and the purity of the resulting isoaldehyde is inevitably low.

For example, when 0.2 wt% of water is contained in the mixed aldehyde product in which the weight ratio of normal aldehyde to isoaldehyde is 9: 1, when isoaldehyde is obtained as a distillate from the top of the column, Neglecting some uncondensed content, about 0.2 x (9 + 1) = 2.0 in the distillate.
The water content will be wt%. Therefore, for example, in order to obtain a high-purity isoaldehyde having a purity of 99.9 wt%, the water content in the mixed aldehyde product needs to be extremely low, for example, less than 0.01 wt%. That is, as mentioned above,
Technical improvement is not easy because it is how to suppress the condensation dehydration reaction which is an undesired side reaction in the hydroformylation reaction which is a generation source of water. In addition, since the raw material oxogas is usually supplied from a party other than the party performing the hydroformylation reaction,
In order to reduce the amount of saturated water vapor contained in oxo gas, equipment such as a dehydrator / dryer must be newly installed, and such equipment has not been implemented in the past because it would be economically disadvantageous. . Therefore, it was practically impossible to produce high-purity isoaldehyde by the methods (1) and (2). On the other hand, JP-A-4-2738
According to the method (3) of No. 41, although an isoaldehyde having a slightly lighter amount can be obtained than the above-mentioned methods (1) and (2), the isoaldehyde is extracted in a stage above the feed stage. However, the water concentration in the column above the feed stage increases as the amount of water contained in the mixed aldehyde product to be fed increases, and water is apt to be entrained in the extracted isoaldehyde. As a countermeasure against this, increasing the reflux amount, increasing the packing height of the distillation column, and increasing the number of stages are economically disadvantageous, and it has been difficult to produce isoaldehyde of substantially high purity.

Therefore, in the step of separating and purifying the mixed aldehyde product, even if the content of light components such as water in the mixed aldehyde product is increased, highly pure isoaldehyde can be obtained stably and economically. A method was desired.

[0013]

Means for Solving the Problems As a result of intensive studies on the above problems, the inventors of the present invention have stably produced high-purity isoaldehyde regardless of the content of light components such as water in the mixed aldehyde product. In order to obtain, (i) separation of normal aldehyde and isoaldehyde (b) separation of light components such as water should be carried out in separate distillation columns, and the order of (a) and (b) should be good as a separation procedure. I found it. That is, the step of separating and purifying the mixed aldehyde product produced by the hydroformylation reaction of propylene or butene into purified normal aldehyde and purified isoaldehyde comprises a two-stage distillation step, and the mixed aldehyde product is first introduced into the first distillation column. And distill it into a light fraction of isaldehyde and aldehyde and normal aldehyde, then
The present invention has been completed by establishing a method for simultaneously obtaining purified normal aldehyde and purified isoaldehyde by distilling and separating into a light fraction of aldehyde and isoaldehyde in a distillation column.

That is, the gist of the present invention is normal aldehyde, isoaldehyde and 0.01 wt% to 5.0 wt% produced by the hydroformylation reaction of propylene or butene.
In a method for producing a high-purity isoaldehyde in which a mixed aldehyde product containing wt% of water is separated and purified into purified normal aldehyde and purified isoaldehyde, the separation and purification step consists of a two-step distillation step, and a mixed aldehyde product is obtained. The distillate of the first distillation column is fed to the first distillation column, and the distillate is separated into the light fraction of isaldehyde and the aldehyde and the normal aldehyde of the bottom product, and the distillate of the first distillation column is fed to the second distillation column. In the method for producing a high-purity isoaldehyde, which is characterized in that a purified normal aldehyde and a purified isoaldehyde are obtained at the same time by distilling and separating into a light fraction of aldehyde as a distillate and an isoaldehyde as a bottom product. Exist in.

The present invention will be described in detail below. The mixed aldehyde product in the present invention is produced by a hydroformylation reaction of propylene or butene, and as a method of separating from the hydroformylation reaction zone,
For example, the method of gas stripping as described in JP-A-52-125103 and the method of distillation as described in JP-A-54-89974 are not particularly limited. However, no matter what means is taken, as a result, most of the unreacted olefin, the solvent and the catalyst liquid containing the by-product high-boiling product have been removed, so that as a component contained in the mixed aldehyde product,
In addition to the main component, mixed aldehyde, very small amount of dissolved gas (hydrogen, carbon monoxide, methane, carbon dioxide, etc.), small amount of unreacted olefin which is light component of aldehyde, paraffins, water, high boiling point of aldehyde A small amount of solvent and a by-product having a high boiling point.

The mixed aldehyde product to be separated and purified in the present invention mainly contains normal aldehyde and isoaldehyde and 0.01 wt% to 5.0 wt% of water, and is a raw material for the hydroformylation reaction. When the olefin is propylene, it includes normal butyraldehyde and isobutyraldehyde, and when the starting olefin is butene, that is, 1-butene or 2-butene,
It includes normal pentyl aldehyde (normal valer aldehyde) and isopentyl aldehyde. Here, isopentyl aldehyde refers to 2-methyl butyraldehyde, 3-methyl butyraldehyde, and viva aldehyde.

The step of separating and purifying this mixed aldehyde product by a two-step distillation step to obtain a purified normal aldehyde and a purified isoaldehyde at the same time will be described below.
First, the mixed aldehyde product is fed to the first distillation column. During this feed stage, the temperature may be raised above about 70 ° C. by heat exchange with other higher temperature process fluids.
The number of stages of the first distillation column is about 40 to about 2 theoretical plates.
The 00th stage is a preferable range and is determined by the required purity of purified normal aldehyde and purified isoaldehyde or economic considerations. That is, if the required purity of purified isoaldehyde or the purity of purified normal aldehyde is not so high, or if the steam cost for heating is low, a low theoretical plate number is sufficient, in the opposite case, that is, the required purified isoaldehyde. If the purity or the purity of purified normal aldehyde is high or the cost of steam for heating is high, a high number of theoretical plates is required.

When the theoretical number of trays is replaced with the actual number of trays, a tray having a general performance has a range of 50 to 200 trays. When the distillation column is used as the packed column, the total height of the packed material is preferably 15 m to 100 m. In the case of packing, the difference in separation performance peculiar to the packing is large, that is, the larger the gas-liquid contact area per unit volume is, the higher the performance becomes, and a high theoretical plate number is realized at a low packing height. Sufficient, and economical low-performance packing is economically practical even at 100 m. If the number of trays or the height of the packing exceeds this range, a large steam cost for heating and unnecessary equipment cost are generated, which is not practical. Also, when a tray is used for a part of the column and a packing is used for a part of the column, the combination method has sufficiently similar separation / purification ability as long as the total height satisfies the theoretical plate number as described above.

From the mixed aldehyde product fed, light components such as water and isoaldehyde are withdrawn as vapor from the top of the column, and dissolved gas (hydrogen.
Most of the unreacted olefins and paraffins (carbon monoxide, methane, carbon dioxide, etc.), as well as uncondensed gas, are purged, and the condensate is separated into oil and water by a decanter. The separated oil layer is an isoaldehyde solution containing about 2 to 4 wt% of saturated water, most of which is returned to the distillation column as reflux and part of which is fed to the second distillation column. On the other hand, the water layer is about 4-6w
Wastewater containing t% of dissolved isaldehyde is sent to the wastewater treatment facility as it is, or is sent to the aldehyde recovery facility in the subsequent step. If the feed-mixed aldehyde product has a small amount of water, the waste water may not be generated before the oil-water separation. Here, the solubility in each layer in oil-water separation is determined by the liquid temperature and the composition of the mixed aldehyde product fed. In the first distillation column, a purified normal aldehyde having a purity of about 99.90 wt% can be obtained as a bottom product, and the purity is controlled by the theoretical plate number, the reflux ratio, and the distillation ratio.

The second distillation column has about 4 to 20 theoretical plates.
The range is the preferred range and is determined by the concentration of light components such as water in the mixed aldehyde product or economic considerations. That is, if the required purity of purified isoaldehyde is not so high, the concentration of light components such as water in the mixed aldehyde product to be fed is low, or the steam cost for heating is low, a low theoretical plate number is sufficient. In the opposite case, that is, when the required purity of the purified isoaldehyde is high, the concentration of light components such as water in the mixed aldehyde product to be fed is high, or the cost of steam for heating is high, the number of theoretical plates is high. Will be needed.

If the theoretical number of trays is replaced with the actual number of trays, then in the case of a tray of general performance, 5 to 3 trays are used.
The range is 0. When using a distillation column as a packed column,
A total fill height of 1.5 to 20 m is preferred. In the case of packing, the difference in separation performance peculiar to the packing is large, that is, the higher the gas-liquid contact area per unit volume is, the higher the performance becomes, and a high theoretical plate number is realized at a low packing height. 5 m is sufficient, and 20 m is economically practical if an inexpensive low-performance packing is used. If the number of trays or the height of the packing exceeds this range, a large steam cost for heating and unnecessary equipment cost are generated, which is not practical. Also, when a tray is used for a part of the column and a packing is used for a part of the column, the combination method has sufficiently similar separation / purification ability as long as the total height satisfies the theoretical plate number as described above.

In the aldehyde product fed to the second distillation column, light components such as water and isoaldehyde are withdrawn as vapor from the top of the column, and most of the aldehyde product is already purged in the first column in the condenser. Dissolved gas (hydrogen, carbon monoxide, methane, carbon dioxide, etc.), unreacted olefin and the rest of paraffins are purged as uncondensed gas, and the condensate is separated into oil and water by a decanter. The separated oil layer is an isoaldehyde liquid containing about 2 to 4 wt% saturated water, and is returned to the second distillation column as a total reflux. On the other hand, the water layer is sent to the waste water treatment facility as it is with waste water containing about 4 to 6 wt% of dissolved isoaldehyde, or is sent to the aldehyde recovery facility in the subsequent step. Here, the solubility in each layer in oil-water separation is determined by the liquid temperature and the composition of the mixed aldehyde product fed. After the light fraction such as water of about 99% or more in the feed liquid is cut in the second distillation column, purified isaldehyde having a purity of about 99.9 wt% is obtained as a bottom liquid. Since the normal distillation is sufficiently separated in the first distillation column, an extremely high-purity isoaldehyde can be obtained, and a high-purity as high as 99.99 wt% can be produced.
There is no particular limitation on the top pressure of both the first tower and the second tower, but when the vacuum pressure is set, a loss of isoaldehyde due to uncondensation occurs in the top condenser using cooling water of about 20 to 30 ° C. Atmospheric pressure or higher is desirable. On the other hand, in the separation of isoaldehyde and normal aldehyde, the lower the pressure, the higher the specific volatility and the smaller the number of theoretical plates required, so atmospheric pressure is most desirable. However, considering the equipment cost, the heat transfer area of the top condenser can be reduced by raising the tower top temperature by pressurizing, and consequently increasing the temperature difference with the cooling water, so 1.0 kg / cm ² G
If the pressurization is to some extent, the number of theoretical plates will increase slightly with the deterioration of separation, but the facility cost will not increase so much and it will be economically viable. Therefore, the column top pressure is 0.001k
g / cm ² G to 1.0 kg / cm ² G is preferable.

[0023]

EXAMPLES The present invention will be described in more detail with reference to examples below, but the present invention is not limited to the following examples as long as the gist thereof is not exceeded. Example 1 A mixed butyraldehyde product was purified using the apparatus of FIG. The composition of the feed liquid in the pipeline (1) was as follows: normal butyraldehyde 88.07 wt%, isobutyraldehyde 11.02 wt%, toluene 0.02 wt%,
Consists of 0.89 wt% water and other dissolved inert gases such as propylene, propane, carbon monoxide, carbon dioxide,
This was led to the first distillation column (15). First distillation column (1
5) consists of 101 trays, and the top pressure is about
It was kept at 0.1 kg / cm ² G. First distillation column (15)
The bottom of the column is heated by the reboiler (18), and the pipe (2)
The overhead gas of (1) was mostly condensed in the condenser (16) and led to the decanter (17) via line (4), and the inert and some uncondensed gas were purged via line (3).
The decanter (17) has a built-in separation weir, and its oil layer is mainly isobutyraldehyde, and most of it is returned to the first distillation column (15) via the line (6) as reflux, and part of it is It was led to the second distillation column (19) via the pipe (8).
On the other hand, the water layer has a conduit (5) to keep the interface of the water layer constant.
Was purged through. Purified normal aldehyde was obtained from line (7). The second distillation column (19) consisted of 14 trays, and the column top pressure was kept at 0.1 kg / cm ² G. The bottom of the second distillation column (19) is heated by the reboiler (22), and the gas at the top of the pipe (9) is stored in the condenser (2).
0) was mostly condensed and led to decanter (21) via line (11), and inert and some uncondensed gas was purged via line (10). The decanter (21) contained a separation weir, the oil layer of which was mainly isobutyraldehyde, and the whole amount of which was refluxed and returned to the second distillation column (19) via the line (13). On the other hand, the water layer was purged via line (12) so as to keep the interface of the water layer constant. Further, purified isobutyraldehyde was obtained from the column bottom through the pipe (14). Table 2 shows the reflux rate of each distillation column, the total calorific value of the reboiler, the flow rate and composition of purified butyraldehyde.
It is shown in FIG.

Comparative Example 1 A mixed butyraldehyde product was purified using the apparatus shown in FIG. The composition of the feed liquid in the pipe (1) was the same as in Example 1, and this was introduced into the distillation column (23). The distillation column (23) was the two distillation columns (101 used in Example 1).
The tray was composed of 115 trays, which is the total number of trays (14 trays, 14 trays), and the top pressure was kept at about 0.1 kg / cm ² G. The bottom of the distillation column (23) is heated by the reboiler (18), the top gas of the pipe (2) is mostly condensed in the condenser (16), and is guided to the decanter (17) via the pipe (4). The inert and some uncondensed gases were then purged via line (3). The decanter (17) has a built-in separation weir, and the oil layer is mainly isobutyraldehyde, and most of it is returned to the distillation column (23) via the pipe (6) as reflux, and part of it is purified isobutyl aldehyde. It was withdrawn as aldehyde from the line (11). On the other hand, the water layer was purged via line (5) so as to keep the interface of the water layer constant. Further, purified normal butyraldehyde was obtained from the bottom of the column through the line (13). The results are shown in Table 1.

Example 2 Example 2 was carried out in the same manner as in Example 1 except that the reflux amount of the distillation column and the total calorific value of the reboiler were set to the conditions shown in Table 1. The results are shown in Table 1. Comparative Example 2 A mixed butyraldehyde product was purified using the apparatus shown in FIG. The composition of the feed liquid in the pipeline (1) was the same as in Example 1, and this was introduced into the distillation column (24). The distillation column (24) is the two distillation columns (101 used in Example 1).
A total of 115 trays, which is the total number of trays and 14 trays), and the top pressure was kept at about 0.1 kg / cm ² G. The bottom of the distillation column (24) is heated by the reboiler (18) with the same total reboiler heat as in Example 2, and the top gas of the line (2) is mostly condensed in the condenser (16), and the line (4) ), Was introduced to the decanter (17), and the inert gas and a part of the uncondensed gas were purged via the line (3). The decanter (17) contained a separation weir, and its oil layer was mainly isobutyraldehyde, and the whole amount was refluxed and returned to the distillation column (24) via the line (6). On the other hand, the water layer was purged via line (5) so as to keep the interface of the water tank constant. From the sidestream, which is two stages below the top of the tower,
Purified isobutyraldehyde was withdrawn as line (11). Further, purified normal butyraldehyde was obtained from the bottom of the column through the line (13). The results are shown in Table 1.

Example 3 Normal butyraldehyde 84.50 wt%, isobutyraldehyde 10.57 wt%, toluene 0.02
wt%, water 4.91 wt%, and other mixed butyraldehyde products consisting of trace amounts of dissolved inert gases such as propylene, propane, carbon monoxide, and carbon dioxide were used as the feed liquid in the pipe (1), and the reflux amount and total reboiler It carried out like Example 1 except having set the heat quantity as the conditions shown in Table-2. Table 2 shows the results.

Comparative Example 3 Similar to Comparative Example 2 except that the feed liquid composition of the pipe (1) was the same as that of Example 3 and the reflux amount and the total reboiler heat amount were set to the conditions shown in Table 2. Carried out. Table 2 shows the results. Example 4 Example 4 was carried out in the same manner as in Example 3 except that the reflux amount of the distillation column and the total heat of the reboiler were set to the conditions shown in Table 2. Table 2 shows the results.

Comparative Example 4 The procedure of Comparative Example 3 was repeated except that the reflux amount and total reboiler calorific value of the distillation column were set as shown in Table 2. Table 2 shows the results.

[0029]

[Table 1] Table-1 ──────────────────────────────────── Example 1 Comparative Example 1 Implementation Example 2 Comparative Example 2 ──────────────────────────────────── Reflux rate First tower kg / H 79 − 140 150 2nd tower kg / H 3.7 81 3.7 − Total heat of reboiler Mcal / H 11 11 19 20 ──────────────────────────── ───────── Purified IBD flow rate g / H 2331 2407 2336 2336 Composition IBD WT% 99.999 96.96 100.00 99.96 NBD WT% 0.001 0.00 0.00 0.00 H ₂ O WT% 0.000 3.04 0.00 0.04 Purified NBD flow rate g / H 18771 18771 18765 18765 Composition IBD WT% 0.04 0.04 0.01 0.01 NBD WT% 99.94 99.94 99.97 99.97 TOL WT% 0.02 0.02 0.02 0.02 ────────────────────────── ───────────

[0030]

[Table 2] Table-2 ──────────────────────────────────── Example 3 Comparative Example 3 Implementation Example 4 Example 4 ──────────────────────────────────── Reflux rate First tower kg / H 79 103 22 − 2nd tower kg / H 21 − 135 160 Total reboiler heat Mcal / H 12 12 20 20 ──────────────────────────── ───────── Purified IBD flow rate g / H 2288 2293 2288 2291 Composition IBD WT% 99.999 99.77 100.00 99.85 NBD WT% 0.001 0.00 0.00 0.00 H ₂ O WT% 0.000 0.23 0.00 0.15 Purified NBD flow rate g / H 18771 18771 18771 18771 Composition IBD WT% 0.04 0.04 0.04 0.04 NBD WT% 99.94 99.94 99.94 99.94 TOL WT% 0.02 0.02 0.02 0.02 ───────────────────────── ─────────── Note: In Table 1 and Table 2, the abbreviations are as follows: IBD: Isobutyrate Laldehyde NBD: Normal butyraldehyde H ₂ O: Water TOL: Toluene

In Table 1, in Example 1 and Comparative Example 1, and in Example 2 and Comparative Example 2, the reboiler had the same total heating vapor amount and the purified normal butyraldehyde had the same purity. is there. We will compare these from the viewpoint of the purity of purified isobutyraldehyde obtained at the same operating cost without changing the quality of purified normal butyraldehyde. First, a comparison between Example 1 and Comparative Example 1 reveals that Comparative Example 1 is obviously less pure than Example 1 because purified isobutyraldehyde contains water of saturated solubility. Next, Example 2 and Comparative Example 2 will be compared under the condition of increasing the reflux amount, which was carried out for the purpose of further increasing the purity of purified isobutyraldehyde. In Example 2, the effect of increasing the reflux amount is remarkable, and the effect is almost 10
Highly purified up to 0 wt%. On the other hand, in Comparative Example 2, water is inevitably contained regardless of a large increase in the reflux amount.

Further, when considering the case where the water concentration in the mixed butyraldehyde product to be fed is increased from Table-2, in Example 3 and Comparative Example 3, and in Example 4 and Comparative Example 4, respectively, The total heating steam amount of the reboiler and the purity of the purified normal butyraldehyde are the same in the group No. First, from the comparison between Example 3 and Comparative Example 3,
In Comparative Example 3, although the amount of normal butyraldehyde in the purified isobutyraldehyde was small, the water content was remarkably large, and as a result, the purity of the purified isobutyraldehyde was significantly lower than that in Example 3. Further, Example 4 and Comparative Example 4 will be compared under the condition of increasing the reflux amount, which was carried out for the purpose of increasing the purity of purified isobutyraldehyde.
In Example 4, the purification amount was increased to almost 100 wt% by increasing the reflux amount. On the other hand, in Comparative Example 4, water is inevitably contained regardless of a large increase in the reflux amount. From the above results, it can be said that the present invention is essentially suitable for producing high-purity isobutyraldehyde.

[0033]

According to the present invention, even if the water content concentration in the mixed aldehyde product is a high concentration (for example, 5 wt%) such as the saturated solubility for aldehyde, the water content in the purified isoaldehyde is high. The amount can be reduced sufficiently. Further, dissolved gases having a boiling point lower than that of water and easily separated, for example, hydrogen, carbon monoxide,
Methane, carbon dioxide, unreacted olefin, paraffin, etc. can be purged from the top of the tower in the first and second towers in a substantially total amount as a gas, so that regardless of the composition of the mixed aldehyde product to be fed, it is always stable. Moreover, highly purified purified isoaldehyde can be produced economically. In addition, too much purification of purified isoaldehyde,
Since it does not lower the purity of the purified normal aldehyde, it is possible to obtain a highly purified purified isoaldehyde and a highly purified purified normal aldehyde at the same time.
Its industrial utility value is great.

[Brief description of drawings]

FIG. 1 is a diagram showing a separation and purification process of the present invention.

FIG. 2 is a diagram showing a separation and purification process of Comparative Example 1.

FIG. 3 is a diagram showing a separation and purification process of Comparative Examples 2 to 4.

[Explanation of symbols]

 1: Feed mixed aldehyde product 16,20: Condenser 17,21: Decanter 15, 19, 23, 24: Distillation column

[Procedure amendment]

[Submission date] August 23, 1994

[Procedure Amendment 1]

[Document name to be amended] Statement

[Name of item to be corrected] 0029

[Correction method] Change

[Correction content]

[0029]

[Table 1] Table-1 ──────────────────────────────────── Example 1 Comparative Example 1 Implementation Example 2 Comparative Example 2 ──────────────────────────────────── Reflux rate First tower kg / H 79 81 140 150 2nd tower kg / H 3.7 − 3.7 − Total heat of reboiler Mcal / H 11 11 19 20 ──────────────────────────── ───────── Purified IBD flow rate g / H 2331 2407 2336 2336 Composition IBD WT% 99.999 96.96 100.00 99.96 NBD WT% 0.001 0.00 0.00 0.00 H ₂ O WT% 0.000 3.04 0.00 0.04 Purified NBD flow rate g / H 18771 18771 18765 18765 Composition IBD WT% 0.04 0.04 0.01 0.01 NBD WT% 99.94 99.94 99.97 99.97 TOL WT% 0.02 0.02 0.02 0.02 ────────────────────────── ───────────

[Procedure Amendment 2]

[Document name to be amended] Statement

[Name of item to be corrected] 0030

[Correction method] Change

[Correction content]

[0030]

[Table 2] Table-2 ──────────────────────────────────── Example 3 Comparative Example 3 Implementation Example 4 Comparative example 4 ──────────────────────────────────── Reflux rate First tower kg / H 79 103 135 160 second column kg / H 21 - 22 - reboiler total amount of heat Mcal / H 12 12 20 20 ─────────────────────────── ───────── Purified IBD flow rate g / H 2288 2293 2288 2291 Composition IBD WT% 99.999 99.77 100.00 99.85 NBD WT% 0.001 0.00 0.00 0.00 H ₂ O WT% 0.000 0.23 0.00 0.15 Purified NBD flow rate g / H 18771 18771 18771 18771 Composition IBD WT% 0.04 0.04 0.04 0.04 NBD WT% 99.94 99.94 99.94 99.94 TOL WT% 0.02 0.02 0.02 0.02 ───────────────────────── ─────────── Note: The abbreviations in Table-1 and Table-2 are as follows: IBD: Isobutyl Aldehyde NBD: Normal butyraldehyde H ₂ O: Water TOL: Toluene

Claims (5)

[Claims] 1. A mixed aldehyde product containing normal aldehyde, isaldehyde and 0.01 wt% to 5.0 wt% of water produced by a hydroformylation reaction of propylene or butene is separated into purified normal aldehyde and purified isaldehyde. In the method for producing high-purity isoaldehyde to be purified, the separation and purification step comprises two distillation steps, and the mixed aldehyde product is supplied to the first distillation column,
By distillative separation into isaldehyde and aldehyde as distillate and normal aldehyde as bottom product,
By supplying the distillate of the first distillation column to the second distillation column and distilling and separating it into a light component of aldehyde as a distillate and an isoaldehyde as a bottom product, purified normal aldehyde and purified isoaldehyde are obtained. A method for producing high-purity isoaldehyde, which comprises simultaneously obtaining 2. The number of plates in the first distillation column is 50 to 200.
A tray having a tray or a packing having a total height of 15 m to 100 m is used, and a tray having 5 to 30 trays or a packing having a total height of 1.5 m to 20 m is used in the second distillation column. The method for producing high-purity isoaldehyde according to 1. 3. Production of high purity iso-aldehyde according overhead pressure of the first distillation column and a second distillation column to claim 1 or 2 which is ^{0.001kg / cm 2 G~1.0kg / cm 2} G Method. 4. The method for producing a high-purity isoaldehyde according to claim 1, wherein the mixed butyraldehyde product produced by the hydroformylation reaction of propylene is separated and purified into purified normal butyraldehyde and purified isobutyraldehyde. . 5. The purity of the purified isoaldehyde is 99.90.
The method for producing a high-purity isoaldehyde according to any one of claims 1 to 4, wherein the content is from wt% to 100.00 wt%.